Under the U.S. Endangered Species Act, a species is classified as endangered, threatened, or recovered based on the extent to which its survival is affected by one or more of five subjective factors. A key criticism of the act is that it makes no reference to quantitative or even qualitative parameters of what constitutes “danger of extinction.” Without objective standards to guide decisionmakers, classification decisions fall...

A bstract Dives of five freely diving ringed seals were classified into three‐dimentional movement types. Horizontally convoluted dives, defined as dives with angular velocity > 15°/sec, appeared to be foraging or social dives. Simple dives that did not include convoluted movements (angular velocity 0.6, on a scale of 0–1) were presumed to be travel dives. Each three‐dimensional dive type was observed with similar frequency in...

A bstract Carrying capacity (K) for the California sea otter ( Enhydra lutris nereis ) was estimated as a product of the density of sea otters at equilibrium within a portion of their existing range and the total area of available habitat. Equilibrium densities were determined using the number of sea otters observed during spring surveys in 1994, 1995, and 1996 in each of three habitat types where sea otters currently exist. P...

Egg strands of perch Perca fluviatilis around the margins of a lake were associated significantly with submerged vegetation. The proportion of dead embryos was significantly higher in egg strands deposited directly on the lake bottom than those on submerged vegetation.